в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:30:05Z

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==Define class with iterator support and direct element access==

<source lang="cpp">/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <algorithm>
#include <functional>
#include <iostream>
#include <cstddef>
using namespace std;

/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}

template<class T, std::size_t thesize>
class carray {
private:
T v[thesize]; // fixed-size array of elements of type T
public:
// type definitions
typedef T value_type;
typedef T* iterator;
typedef const T* const_iterator;
typedef T& reference;
typedef const T& const_reference;
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
// iterator support
iterator begin() { return v; }
const_iterator begin() const { return v; }
iterator end() { return v+thesize; }
const_iterator end() const { return v+thesize; }
// direct element access
reference operator[](std::size_t i) { return v[i]; }
const_reference operator[](std::size_t i) const { return v[i]; }
// size is constant
size_type size() const { return thesize; }
size_type max_size() const { return thesize; }
// conversion to ordinary array
T* as_array() { return v; }
};
int main()
{
carray<int,10> a;
for (unsigned i=0; i<a.size(); ++i) {
a[i] = i+1;
}
PRINT_ELEMENTS(a);
reverse(a.begin(),a.end());
PRINT_ELEMENTS(a);
transform(a.begin(),a.end(), // source
a.begin(), // destination
negate<int>()); // operation
PRINT_ELEMENTS(a);
}</source>
<pre class=codeResult>1 2 3 4 5 6 7 8 9 10
10 9 8 7 6 5 4 3 2 1
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1</pre>

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в 14:21, 25 мая 2010

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